As computer technology continues to advance, electronic components such as central processing units (CPUs) of computers are made to provide faster operational speed and greater functional capabilities. When a CPU operates at a high speed in a computer enclosure, its temperature increases greatly and dramatically. It is desirable to dissipate the generated heat quickly, for example, by using a heat sink attached to the CPU in the enclosure. This allows the CPU and other electronic components in the enclosure to function within their normal operating temperature ranges, thereby assuring the quality of data management, storage and transfer. Generally, a locking device is required for mounting the heat sink to the CPU.
FIG. 5 shows a conventional locking device for mounting a heat sink 200 to a CPU 600. The CPU 600 is mounted on a printed circiut board 500 which defines mounting holes 502 about the CPU 600. The heat sink 200 forms a pair of extension arms 202 each of which defines a through hole 204 corresponding to one of the mounting holes 502 of the printed circuit board 500. The locking device comprises a pair of push-in pins 300 and a pair of springs 400 installed around the pins 300 respectively. In assembly, the pins 300 are inserted and extend sequentially through the respective springs 400, through holes 204 of the heat sink 200 and mounting holes 502. The bottom ends of the pins 300 are engaged with the printed circuit board 500 below the mounting holes 502. The springs 400 are compressed between the top ends of the pins 300 and the heat sink 200 to thereby exert downward force to the heat sink 200 to cause the heat sink 200 to intimately contact with the CPU 600.
However, it is difficult to detach the push-in pins 300 from the printed circuit board 500 in disassembly. Furthermore, the springs 400 are prone to fatigue after a long time using. As a result, the heat sink 200 is not capable of intimately contacting with the CPU 600 in an acceptably long-used period.